This application claims the benefit of Korean Application No. 2002-21440, filed on Jul. 9, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a turbofan and a mold used to manfacture the same, and more particularly to a turbofan and a mold used to manfacture the same, which enables the turbofan to be integrally molded by a single molding process.
2. Description of the Prior Art
In general, a turbofan is a type of centrifugal fan, which is adapted to blow air by centrifugal force of the air generated from rotating blades. As illustrated in FIG. 1, such a turbofan comprises a circular rotating plate 1 having a central hub 1a to which a rotating shaft of a driving motor (not shown) is coupled, a plurality of blades 2 which are radially disposed at a periphery of the circular rotating plate 1 with regular intervals therebetween such that the blades 2 are positioned to be perpendicular to the rotating plate 1, and a ring-shaped shroud 3 coupled to free ends of the blades 2 to support the blades 2. In the turbofan, the plurality of blades 2 are orientated to be inclined by a certain angle with respect to respective tangential lines on the periphery of the rotating plate 1.
The turbofan is usually produced by a plastic injection molding process. Because the turbofan is provided with a number of undercuts at its blades 2, which cause separation of a mold therefrom to be difficult, the turbofan is hard to integrally mold by only one molding process. To overcome this disadvantage, a conventional turbofan is produced in such a way that a component xe2x80x9cAxe2x80x9d, in which a rotating plate 1 and blades 2 are integrally molded, and a shroud 3 are first molded by separate molds, and the component xe2x80x9cAxe2x80x9d and the shroud 3 are combined to each other by ultrasonic fusion or heat fusion in a subsequent procedure, as illustrated in FIG. 2.
However, since such conventional turbofans are produced by a process of molding a plurality of components in separate molds and joining the components together, productivity of the conventional turbofans is decreased due to the complicated manufacturing process. Furthermore, since the conventional process of manufacturing turbofans requires a plurality of molds for separate components, manufacturing cost is considerably increased due to production of the molds. In addition, since a plurality of components are joined to one another afterward, defective fraction of products is increased by poor assembly.
Accordingly, it is an object of the present invention to provide a turbofan and a mold used to manfacture the same which enables the turbofan to be integrally produced by only one molding process so as to improve productivity, to reduce manufacturing cost and to improve quality of products.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other objects of the present invention are achieved by providing a turbofan comprising: a rotating plate coupled to a shaft of a driving motor at its center; a plurality of blades which are radially disposed at and integrally formed with a periphery of the rotating plate; a ring-shaped shroud integrally formed with front ends of the blades to face the rotating plate; and a plurality of core holes formed at the rotating plate at an area corresponding to the shroud to allow cores to shape undercut portions of the blades to pass therethrough.
A radial width of each of the core holes may be equal to a radial width of the shroud, and each of the core holes may be shaped to have a triangular form.
An external diameter of the rotating plate may be larger than an external diameter of the shroud.
The foregoing and other objects of the present invention are also achieved by providing a mold used to manfacture a turbofan including a rotating plate coupled to a shaft of a driving motor at its center, a plurality of blades which are radially disposed at and integrally formed with a periphery of the rotating plate, and a ring-shaped shroud integrally formed with front ends of the blades to face the rotating plate, the mold comprising: a first mold part having a rear molding member to shape a rear portion of the rotating plate; a second mold part to be combined with the first mold part and having a front molding member to shape a front portion of the turbofan at an area corresponding to the rear molding member; a plurality of slide cores adapted to be radially moved to shape an inner surface of the shroud, outer portions of a front surface of the rotating plate, and outer surfaces of the blades; and a plurality of auxiliary cores extending to the inner surface of the shroud from the rear molding member of the first mold part to shape undercut portions of inner surfaces of the blades.
The front molding member of the second mold part may include an outer molding portion to shape a front surface of the shroud, a mediate molding portion to shape an inner edge of the shroud, and an inner molding portion to shape a front surface of the rotating plate, defined by an inner edge of the shroud.
The inner molding portion of the second mold part may be provided with a plurality of blade molding slits, which inwardly extend from its peripheral surface to shape the leading ends of the blades.
Each of the slide cores may be provided at its molding surface with a plurality of blade molding portions at its molding surface to shape outer surfaces of a plurality of adjacent blades concurrently.
The slide cores may be provided at either of the first and second mold parts to be radially moved, and the other of the first and second mold parts may be provided with a slanted pin inclined with respect to a moving direction of the second mold part to radially move the slide cores, one of the slide cores being provided with a slanted hole corresponding to the slanted pin.
Each of the auxiliary cores may be shaped to have a triangular form in section.